The present invention relates to touch panels, and more particularly, to methods and apparatus for detecting a user's touch on a touch panel.
Touch panels have been widely used in portable devices. For example, they can be implemented as displays or fingerprint readers which are utilized in personal digital assistants (PDAs) and laptop computers. Typically, analog-to-digital converters (ADCs) are utilized for respectively converting signals from different locations on a touch panel into digital values in order to detect a user's touch on the touch panel. According to a related art method, the location where the user touches on the touch panel can be determined by detecting a maximum of the digital values. More particularly, it is suggested by the related art method that the location corresponding to the maximum that one of the ADCs' outputs is substantially the location where the user touches on the conventional touch panel.
By the architecture provided by the related art, a large dynamic range for each of the ADCs is required in order to detect a possible maximum of the digital values, thereby increasing the associated cost. In practice, if any of the ADCs does not linearly convert the signal, low accuracy of the detection mentioned above will be introduced. As a result, a large linear region for each of the ADCs is also required.
Due to strict requirements of the ADCs, such as the large dynamic range and the large linear region, the overall cost of a portable device implemented with a conventional touch panel cannot be reduced further. Thus, a novel method and associated apparatus are required for solving the related art problems.